An adolescent girl presented with inappetence. Upper gastrointestinal endoscopy showed rough and cracked mucosa at the gastric antrum with a scarred duodenal ulcer, and a biopsy sample demonstrated abundant eosinophils. We therefore diagnosed the patient as having eosinophilic gastroenteritis. Eradication therapy for Helicobacter pylori (H. pylori) did not improve her symptoms; however, proton pump inhibitor therapy was effective in resolving her chief complaints. There are several reports of eosinophilic gastroenteritis complicated with H. pylori infection in which the association between eradication therapy and the patient's symptoms is unclear. In the present case, the patient's symptoms did not improve with eradication therapy, and there appeared to be no relationship between the two.